The free radical polymerization of olefins and polar monomers such as acrylates in nonaqueous media using Brönsted or Lewis acids as catalysts is well known. Generally, such polymerizations result in low molecular weight polymers or oligomers that have some tendency to alternate between the nonpolar olefin and the polar monomer, often an acrylate. Typically, water is meticulously removed before the Brönsted or Lewis acid is added to the polymerization because of the reactivity between the acid and water.
Ethylenically unsaturated olefins without heteroatom substitution typically have low copolymerization rates with polar monomers such as acrylates. The copolymerization technology of, olefins with polar monomers is reviewed in WO 03/070783 and WO 2005/054305 both owned by PPG Industries Ohio, Inc. The olefins are described as electron donating type monomers and the acrylates are described as electron accepting monomers. Styrene copolymerization with maleic anhydride is discussed in WO 03/070783 in paragraph [0002] and described as forming charge transfer complexes and resulting in some alternating sequences. Styrene is a somewhat nonpolar monomer that does readily copolymerize with acrylates and other polar monomers by free-radical mechanisms even in the absence of charge complexation. While styrene does contribute to a more hydrophobic acrylate polymer, the resulting polymers have high glass transition temperature(s) and are not useful for many applications where soft-flexible film formation is desired. Therefore, there is a desire to have more hydrophobic olefins copolymerize with acrylates and other polar co-monomers to form moderate to low glass transition temperature polymers for use in many ink, adhesive, and coating applications.
In WO 03/070783, Examples A and B of the copolymers they feed 3 or 4 different charges into a reaction vessel over several hours maintaining a temperature of 140-160° C. and pressures from 5 psi to 62 psi in Example A and 40 to 360 psi in Example B. Molecular weights were number averages of 2293 and 4274 while the weight averages were 8317 and 12,856 gram/mole. These copolymers were blended with more conventional latexes and made into curable film forming compositions.
In WO 2005/054305, Examples 1-4 were 25/20155 w/w/w/ of isobutylene/hydroxypropyl acrylate/butyl acrylate polymerized into a copolymer by the method of the patent application. The monomers and di-t-amyl peroxide were prepared in three separate feed tanks and commingled in a teed line just prior to addition to the 5-gallon stirred reactor. The reactor was maintained between 200 and 210° C., at a pressure of 500 psi for a residence time of 16 to 25 minutes. The resulting polymer was reported to have a composition of 21 wt. % isobutylene, 27 wt. % hydroxypropyl acrylate, and 52 wt. % butyl acrylate. The copolymer was reported to have number average molecular weights between 1446 and 1699 and weight average molecular weights between 2781 and 3441 g/mole.
It would be desirable to copolymerize ethylenically unsaturated olefins of 4 to 30 carbon atoms with polar monomers such as acrylate monomers in large commercial reactors in aqueous media at 1 or 2 atmosphere pressure. It is also desired to make polymers over 50,000 molecular weight, preferably over 100,000 molecular weight to obtain optimum desired properties.